homework help~

[sheilaw]

determine is convergence or divergence?
1.sum[n=1,infinity][(10^10n^20/(n^3+1)]
2.sum[n=1,infinity][1/Ln(n+1)]
3.sum[n=1,infinity][1/(n^2Ln(n=1))]
4.sum[n=2,infinity][arctann/n]
5.sum[n=1,infinity][1/(n+2^(1/2))]

that's my cal 2 homework, but i dont know how to start them. please help me!

 

[Deleted member 4993]

determine is convergence or divergence?
1.sum[n=1,infinity][(10^10n^20/(n^3+1)]
2.sum[n=1,infinity][1/Ln(n+1)]
3.sum[n=1,infinity][1/(n^2Ln(n=1))]
4.sum[n=2,infinity][arctann/n]
5.sum[n=1,infinity][1/(n+2^(1/2))]

that's my cal 2 homework, but i dont know how to start them. please help me!

What are the methods of testing - that you have been taught?

Please show us your work, indicating exactly where you are stuck - so that we know where to begin to help you

 

[sheilaw]

the camparison test, and the limit comparison test
but i dont no how to use these two tests.

 

[Deleted member 4993]

the camparison test, and the limit comparison test
but i dont no how to use these two tests.

Please tell me - what is a comparison test? What do you do - what do you compare?

What about ratio test - have you been taught that?

 

[fred2028]

the camparison test, and the limit comparison test
but i dont no how to use these two tests.

These 2 tests are based on the assumption you know another function that relates to this one. We are learning about this too. Comparison test, in non-math terms:

If a function g(x) lies graphically above your f(x) and g(x) converges, then f(x) converges. Both functions > 0.
If a function g(x) lies graphically below your f(x) and g(x) diverges, then f(x) diverges. Both functions > 0.

That's what I remember of it, someone correct me if I'm wrong.
Limit comparison:

Find another function that you know whether diverges/converges. If you divide one limit by the other (doesn't matter how), and the answer > 0, then both functions do the same, i.e. if your 2nd function diverges then your original diverges also.

Hope I was of help.